How can people with more information be both more confident and more wrong?

I become truly frustrated when faced with someone who insists they are an expert in something they know absolutely nothing about. As a believer in evidence, my first instinct is to provide them with more information, but perhaps this isn’t always a good idea.

The overconfidence effect is a decision-making bias where a person’s confidence about a decision is greater than their accuracy when making it. A great article by Hall, Ariss and Todorov (2007) The illusion of knowledge: When more information reduces accuracy and increases confidence asked participants to predict and bet on basketball games and found that increasing information didn’t cause the expected effects. Their findings have implications for settings such as political campaigns, where the decision to provide voters with an abundance of accurate information countering the false claims may not have the desired effect. Nyhan and Reifler’s paper When Corrections Fail: The Persistence of Political Misperceptions describes this ‘backfire effect’ in which corrections to mock news articles reinforced belief in the original, incorrect version.

So sometimes holding back on the evidence lesson is a good idea with an ignorant audience. And perhaps if I’m so sure I’m right, I might have it so wrong I should be keeping my mouth shut anyway!